Re: [PATCH ima-evm-utils v2 09/12] Fix potential use after free in read_tpm_banks()

From: Stefan Berger <stefanb@linux.ibm.com>
To: Mimi Zohar <zohar@linux.ibm.com>, linux-integrity@vger.kernel.org
Cc: Petr Vorel <pvorel@suse.cz>, Vitaly Chikunov <vt@altlinux.org>
Subject: Re: [PATCH ima-evm-utils v2 09/12] Fix potential use after free in read_tpm_banks()
Date: Tue, 13 Sep 2022 12:38:46 -0400	[thread overview]
Message-ID: <c7c0e63d-8c7f-2c75-9247-cc93758ce946@linux.ibm.com> (raw)
In-Reply-To: <20220906195021.854090-10-zohar@linux.ibm.com>


On 9/6/22 15:50, Mimi Zohar wrote:
> On failure to read TPM 2.0 bank PCRs 'errmsg' is not properly set to
> NULL after being freed.  Fix potential use after free.
> 
> Fixes: 3472f9ba9c05 ("ima-evm-utils: read the PCRs for the requested TPM banks")
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
> ---
>   src/evmctl.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/src/evmctl.c b/src/evmctl.c
> index fa588e0caba2..a497b1a468d6 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -2075,6 +2075,7 @@ static int read_tpm_banks(int num_banks, struct tpm_bank_info *bank)
>   				log_debug("Failed to read %s PCRs: (%s)\n",
>   					  bank[i].algo_name, errmsg);
>   				free(errmsg);
> +				errmsg = NULL;
>   				bank[i].supported = 0;
>   			}
>   		}